1. Field of the Invention
This invention relates generally to the manufacture of semiconductor devices. More specifically, this invention relates to a method of marking each die on a wafer during the manufacture of semiconductor devices with identification information. Even more specifically, this invention relates to a method of marking each die on a wafer during the manufacture of semiconductor devices with identification information that can identify and distinguish each die from every other die manufactured by the same manufacturer.
2. Discussion of the Related Art
Modern electronic systems, such as computer systems typically contain several semiconductor devices, each of which has a specific function or specific functions to perform. Each of these functions must be performed correctly or the electronic system will not function properly. When one of the modern electronic systems fails, it is desirable for the manufacturer of the electronic system to determine which semiconductor device caused the failure. In addition, when the specific semiconductor device that caused the failure is identified, it is desirable for the manufacturer of the specific semiconductor device to be able to identify in which manufacturing lot the semiconductor device was manufactured during testing procedures such as customer return failure analysis. These testing procedure assist the manufacturer of the semiconductor device to determine the manufacturing dependent anomalies associated with that individual die. These anomalies include inline defects, bit map failure data, high/low WET data, which could immediately point to the root cause of the failure, or at least provide information that would allow for intelligent de-processing to confirm a probable cause of the failure. The difficulty with retaining this level of accounting is the massive logistic concerns involved with keeping track of the millions of semiconductor die through the various assembly operations in a typical assembly house. Until the die is finally packaged and marked, there is no current method of monitoring these identities.
For example, computer systems typically contain one or more microprocessors that execute code or instructions for an operating system, applications programs and other hardware and software elements of the computer system. Such a microprocessor or microprocessors are at the core of what is referred to as a central processing unit (CPU). In addition, the CPU is typically and preferably implemented on a single semiconductor integrated circuit chip. Such a semiconductor integrated circuit chip is referred to as a CPU, a CPU chip, or simply as a microprocessor.
Semiconductor integrated circuit chip manufacturers produce and market microprocessors having a variety of available clock speeds. In general, a higher clock speed for a microprocessor yields higher instruction execution performance. The higher instruction execution performance is valuable to the end user and certain end users, depending upon for what application the system is to be used, are willing to pay a premium for the higher instruction execution performance that is obtainable with a higher clock speed. For example, multimedia applications increasingly require faster clock speeds. Applications that require high clock speed microprocessors include applications that provide full motion video, applications that provide complex graphics, etc.
It is critically important that a microprocessor is not run at clock speeds in excess of the speed determined by the manufacturer's testing procedure and guaranteed by the manufacturer. Operating the microprocessor above the manufacturer's specifications creates potential reliability issues that can cause the microprocessor and/or end user applications to malfunction and to fail.
It has been found that microprocessors that have been certified and sold at a particular speed have been re-marked at a higher speed. These re-marked microprocessors are "over-clocked," that is, they are being run above the manufacturer's specified speed. By doing so, the system with the over-clocked microprocessor can be sold at a premium which is unjustified. Failure of such systems to operate properly at the mismarked speed cause end user dissatisfaction with the system. This end user dissatisfaction is usually directed at the manufacturer and results in damage to the manufacturer's reputation, goodwill, and can affect future sales. The sale of such mismarked over-clocked systems can cost microprocessor chip manufacturers millions of dollars in lost sales (of properly marked higher speed microprocessors as well as future sales) and in repair and replacement costs. In addition, manufacturers have sometime been put in the position of having to replace mismarked parts to protect their reputation.
There are problems with computer systems because the semiconductor integrated circuit chip manufacturers typically evolve microprocessor architectures on a development schedule independently of the schedule of new software releases by vendors of operating systems and BIOS. As a consequence, the performance information for a particular operating system or BIOS release may not coincide with the performance information for newer microprocessor chips. Such an information mismatch can cause an operating system or BIOS to misidentify the performance information for a particular microprocessor installed in a system. Because the rate of improvements in microprocessor architectures and process technologies has accelerated resulting in an increased likelihood that an operating system or BIOS will misidentify the performance of the microprocessor installed in a particular system due to such an information mismatch.
Another problem that is becoming more prevalent in the semiconductor industry is the theft of semiconductor devices. There is currently no method of positively identifying semiconductor devices such as microprocessors as being stolen property because semiconductor devices from wafer look exactly alike. This means that millions of semiconductor devices look exactly alike.
Therefore, what is needed is a method of identifying individual die for failure analysis, detection of overclocking and positive identification of stolen die.